Various map apparatus have been proposed for indicating destination locations. An example is the indication on a map of the location of a store relative to the location of the user of the system, as in a shopping mall. Other map apparatus have been designed to indicate routes and information pertaining to those routes such as for a city bus or subway system.
U.S. Pat. No. 1,637,685 to Cowles uses lights to illuminate selected areas on a map. U.S. Pat. No. 1,655,294 to Robinson indicates business locations that have been selected from a directory. U.S. Pat. No. 1,424,840 to Pardee indicates station routes on a map. U.S. Pat. No. 2,487,318 to Elliot utilizes a traveling column of light cells to indicate destinations on a map. U.S. Pat. No. 2,688,741 to Saltarelli concerns indications of travel routes along with information as to vehicle numbers and transfer requirements.
A need exists in modern cities for emergency vehicles to be informed of direct routes to destinations so that their arrival is expedited. Such vehicles may be fire trucks, emergency ambulances and police cars. The operators of these vehicles are usually familiar with the primary streets servicing their areas but need information as to the most effective secondary street intersections, with these primary streets, to use.